A very efficient java hash algorithm, based on the BuzHash algoritm : hashCode « Class Definition « Java Tutorial

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Java Tutorial » Class Definition » hashCode 
5.34.7.A very efficient java hash algorithm, based on the BuzHash algoritmPrevious/Next
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 
 *      http://www.apache.org/licenses/LICENSE-2.0
 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * A very efficient java hash algorithm, based on the BuzHash algoritm by Robert
 * Uzgalis (see http://www.serve.net/buz/hash.adt/java.000.html for more
 * information). BuzHash is Copyright (c)1996 Robert Uzgalis, All Rights
 * Reserved. Used with kind permission of the author
 
 @version $Id: HashUtil.java 587751 2007-10-24 02:41:36Z vgritsenko $
 */
public final class HashUtil {

  private static long initial_hash = 0xe12398c6d9ae3b8aL// initial values

  private static long mix_master[/* 0:255 */{
  /* 000 */0x4476081a7043a46fL0x45768b8a6e7eac19L0xebd556c1cf055952L,
  /* */0x72ed2da1bf010101L0x3ff2030b128e8a64L,
  /* 005 */0xcbc330238adcfef2L0x737807fe42e20c6cL0x74dabaedb1095c58L,
  /* */0x968f065c65361d67L0xd3f4018ac7a4b199L,
  /* 010 */0x954b389b52f24df2L0x2f97a9d8d0549327L0xb9bea2b49a3b180fL,
  /* */0xaf2f42536b21f2ebL0x85d991663cff1325L,
  /* 015 */0xb9e1260207b575b9L0xf3ea88398a23b7e2L0xfaf8c83ffbd9091dL,
  /* */0x4274fe90834dbdf9L0x3f20b157b68d6313L,
  /* 020 */0x68b48972b6d06b93L0x694837b6eba548afL0xeecb51d1acc917c9L,
  /* */0xf1c633f02dffbcfaL0xa6549ec9d301f3b5L,
  /* 025 */0x451dc944f1663592L0x446d6acef6ce9e4fL0x1c8a5b3013206f02L,
  /* */0x5908ca36f2dc50f7L0x4fd55d3f3e880a87L,
  /* 030 */0xa03a8dbeabbf065dL0x3ccbbe078fabcb6dL0x1da53a259116f2d0L,
  /* */0xfb27a96fcb9af152L0x50aba242e85aec09L,
  /* 035 */0x24d4e414fc4fc987L0x83971844a9ce535eL0xc26a3fdeb849398eL,
  /* */0xc2380d044d2e70d8L0xab418aa8ae19b18fL,
  /* 040 */0xd95b6b9247d5ebeaL0x8b3b2171fdc60511L0xe15cd0ae3fcc44afL,
  /* */0x5a4e27f914a68f17L0x377bd28ca09aafdcL,
  /* 045 */0xbbeb9828594a3294L0x7c8df263ae1de1b9L0xba0a48a5fd1c1dd0L,
  /* */0x57cc1b8818b98ee6L0x8c570975d357dabcL,
  /* 050 */0x76bdcd6f2e8826aaL0x529b15b6ec4055f1L0x9147c7a54c34f8a9L,
  /* */0x2f96a7728170e402L0xe46602f455eca72eL,
  /* 055 */0x22834c4dd1bde03fL0x2644cf5a25e368ffL0x907c6de90b120f4aL,
  /* */0xadfe8ba99028f728L0xa85199ae14df0433L,
  /* 060 */0x2d749b946dd3601eL0x76e35457aa052772L0x90410bf6e427f736L,
  /* */0x536ad04d13e35041L0x8cc0d76769b76914L,
  /* 065 */0xae0249f6e3b3c01cL0x1bdfd075307d6fafL0xd8e04f70c221deccL,
  /* */0x4ab23622a4281a5dL0x37a5613da2fcaba7L,
  /* 070 */0x19a56203666d4a9fL0x158ffab502c4be93L0x0bee714e332ecb2fL,
  /* */0x69b71a59f6f74ab0L0x0fc7fc622f1dfe8fL,
  /* 075 */0x513966de7152a6f9L0xc16fae9cc2ea9be7L0xb66f0ac586c1899eL,
  /* */0x11e124aee3bdefd7L0x86cf5a577512901bL,
  /* 080 */0x33f33ba6994a1fbdL0xde6c4d1d3d47ff0dL0x6a99220dc6f78e66L,
  /* */0x2dc06ca93e2d25d2L0x96413b520134d573L,
  /* 085 */0xb4715ce8e1023afaL0xe6a75900c8c66c0aL0x6448f13ad54c12edL,
  /* */0xb9057c28cf6689f0L0xf4023daf67f7677aL,
  /* 090 */0x877c2650767b9867L0xb7ea587dcd5b2341L0xc048cf111733f9bcL,
  /* */0x112012c15bc867bfL0xc95f52b1d9418811L,
  /* 095 */0xa47e624ee7499083L0x26928606df9b12e8L0x5d020462ec3e0928L,
  /* */0x8bbde651f6d08914L0xd5db83db758e524aL,
  /* 100 */0x3105e355c000f455L0xdd7fe1b81a786c79L0x1f3a818c8e012db1L,
  /* */0xd902de819d7b42faL0x4200e63325cda5f0L,
  /* 105 */0x0e919cdc5fba9220L0x5360dd54605a11e1L0xa3182d0e6cb23e6cL,
  /* */0x13ee462c1b483b87L0x1b1b6087b997ee22L,
  /* 110 */0x81c36d0b877f7362L0xc24879932c1768d4L0x1faa756e1673f9adL,
  /* */0x61651b24d11fe93dL0x30fe3d9304e1cde4L,
  /* 115 */0x7be867c750747250L0x973e52c7005b5db6L0x75d6b699bbaf4817L,
  /* */0x25d2a9e97379e196L0xe65fb599aca98701L,
  /* 120 */0x6ac27960d24bde84L0xdfacc04c9fabbcb6L0xa46cd07f4a97882bL,
  /* */0x652031d8e59a1fd8L0x1185bd967ec7ce10L,
  /* 125 */0xfc9bd84c6780f244L0x0a0c59872f61b3ffL0x63885727a1c71c95L,
  /* */0x5e88b4390b2d765cL0xf0005ccaf988514dL,
  /* 130 */0x474e44280a98e840L0x32de151c1411bc42L0x2c4b86d5aa4482c2L,
  /* */0xccd93deb2d9d47daL0x3743236ff128a622L,
  /* 135 */0x42ed2f2635ba5647L0x99c74afd18962dbdL0x2d663bb870f6d242L,
  /* */0x7912033bc7635d81L0xb442862f43753680L,
  /* 140 */0x94b1a5400aeaab4cL0x5ce285fe810f2220L0xe8a7dbe565d9c0b1L,
  /* */0x219131af78356c94L0x7b3a80d130f27e2fL,
  /* 145 */0xbaa5d2859d16b440L0x821cfb6935771070L0xf68cfb6ee9bc2336L,
  /* */0x18244132e935d2fdL0x2ed0bda1f4720cffL,
  /* 150 */0x4ed48cdf6975173cL0xfd37a7a2520e2405L0x82c102b2a9e73ce2L,
  /* */0xadac6517062623a7L0x5a1294d318e26104L,
  /* 155 */0xea84fe65c0e4f061L0x4f96f8a9464cfee9L0x9831dff8ccdc534aL,
  /* */0x4ca927cd0f192a14L0x030900b294b71649L,
  /* 160 */0x644b263b9aeb0675L0xa601d4e34647e040L0x34d897eb397f1004L,
  /* */0xa6101c37f4ec8dfcL0xc29d2a8bbfd0006bL,
  /* 165 */0xc6b07df8c5b4ed0fL0xce1b7d92ba6bccbeL0xfa2f99442e03fe1bL,
  /* */0xd8863e4c16f0b363L0x033b2cccc3392942L,
  /* 170 */0x757dc33522d6cf9cL0xf07b1ff6ce55fec5L0x1569e75f09b40463L,
  /* */0xfa33fa08f14a310bL0x6eb79aa27bbcf76bL,
  /* 175 */0x157061207c249602L0x25e5a71fc4e99555L0x5df1fe93de625355L,
  /* */0x235b56090c1aa55dL0xe51068613eaced91L,
  /* 180 */0x45bd47b893b9ff1eL0x6595e1798d381f2dL0xc9b5848cbcdb5ba8L,
  /* */0x65985146ff7792bcL0x4ab4a17bf05a19a0L,
  /* 185 */0xfd94f4ca560ffb0cL0xcf9bad581a68fa68L0x92b4f0b502b1ce1aL,
  /* */0xbcbec0769a610474L0x8dbd31ded1a0fecbL,
  /* 190 */0xdd1f5ed9f90e8533L0x61c1e6a523f84d95L0xf24475f383c110c4L,
  /* */0xdb2dffa66f90588dL0xac06d88e9ee04455L,
  /* 195 */0xa215fc47c40504baL0x86d7caebfee93369L0x9eaec31985804099L,
  /* */0x0fba2214abe5d01bL0x5a32975a4b3865d6L,
  /* 200 */0x8cceebc98a5c108fL0x7e12c4589654f2dcL0xa49ad49fb0d19772L,
  /* */0x3d142dd9c406152bL0x9f13589e7be2b8a5L,
  /* 205 */0x5e8dbac1892967adL0xcc23b93a6308e597L0x1ef35f5fe874e16aL,
  /* */0x63ae9cc08d2e274fL0x5bbabee56007fc05L,
  /* 210 */0xabfd72994230fc39L0x9d71a13a99144de1L0xd9daf5aa8dcc89b3L,
  /* */0xe145ec0514161bfdL0x143befc2498cd270L,
  /* 215 */0xa8e192557dbbd9f8L0xcbeda2445628d7d0L0x997f0a93205d9ea4L,
  /* */0x01014a97f214ebfaL0x70c026ffd1ebedafL,
  /* 220 */0xf8737b1b3237002fL0x8afcbef3147e6e5eL0x0e1bb0684483ebd3L,
  /* */0x4cbad70ae9b05aa6L0xd4a31f523517c363L,
  /* 225 */0xdb0f057ae8e9e8a2L0x400894a919d89df6L0x6a626a9b62defab3L,
  /* */0xf907fd7e14f4e201L0xe10e4a5657c48f3fL,
  /* 230 */0xb17f9f54b8e6e5dcL0x6b9e69045fa6d27aL0x8b74b6a41dc3078eL,
  /* */0x027954d45ca367f9L0xd07207b8fdcbb7ccL,
  /* 235 */0xf397c47d2f36414bL0x05e4e8b11d3a034fL0x36adb3f7122d654fL,
  /* */0x607d9540eb336078L0xb639118e3a8b9600L,
  /* 240 */0xd0a406770b5f1484L0x3cbee8213ccfb7c6L0x467967bb2ff89cf1L,
  /* */0xb115fe29609919a6L0xba740e6ffa83287eL,
  /* 245 */0xb4e51be9b694b7cdL0xc9a081c677df5aeaL0x2e1fbcd8944508ccL,
  /* */0xf626e7895581fbb8L0x3ce6e9b5728a05cbL,
  /* 250 */0x46e87f2664a31712L0x8c1dc526c2f6acfaL0x7b4826726e560b10L,
  /* */0x2966e0099d8d7ce1L0xbb0dd5240d2b2adeL0x0d527cc60bbaa936L };

  /**
   * This is buzhash the hash function on which most other Hash methods are
   * built.
   */
  private static long buzhash(StringBuffer arg) {
    /* Hash StringBuffer */
    long h = initial_hash;
    for (int i = 0; i < arg.length(); ++i)
      h = (h << 1(h >>> 63^ mix_master[(arg.charAt(i(arg.charAt(i>>> 8)) 0xff];
    return h;
  }

  /**
   * This is buzhash the hash function on which most other Hash methods are
   * built.
   */
  private static long buzhash(String arg) {
    /* Hash StringBuffer */
    long h = initial_hash;
    for (int i = 0; i < arg.length(); ++i)
      h = (h << 1(h >>> 63^ mix_master[(arg.charAt(i(arg.charAt(i>>> 8)) 0xff];
    return h;
  }

  /**
   * Hash a String.
   
   @param arg
   *          The String to be hashed
   @return The hash for the input.
   */
  public static long hash(String arg) {
    // Make Hash from String
    return buzhash(arg);
  }

  /**
   * Hash a String.
   
   @param arg
   *          The String represented by the StringBuffer to be hashed
   @return The hash for the input.
   */
  public static long hash(StringBuffer arg) {
    // Make Hash from StringBuffer
    return buzhash(arg);
  }

}
5.34.hashCode
5.34.1.Implement hashCode using commons-lang
5.34.2.Comparing Object Values Using Hash Codes
5.34.3.Get the identity hash codes
5.34.4.Null Safe Hash Code
5.34.5.Secure Hash
5.34.6.Get hash code for primitive data types
5.34.7.A very efficient java hash algorithm, based on the BuzHash algoritm
5.34.8.Computing hash codes
5.34.9.Returns an integer hash code representing the given double array value.
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